For its full-frame DSMLs EOS R5 and R6, Canon has released new firmwares in March, which should be mentioned here for the sake of completeness. Common to both firmware updates is improved eye detection stability and optimized autofocus tracking when shooting moving subjects. Canon does not specify whether the improvements only apply to the photo or also to the video function. We therefore optimistically assume that this applies to both photo and video users.
The Canon EOS R5 update also improved autofocus accuracy when the RF1.4x extender or RF2x extender is attached to the RF800mm F5.6 L IS USM and RF1200mm F8 L IS USM lenses.
The Canon EOS R5 firmware version 1.5.2 can be found 
free download here
The Canon EOS R6 firmware update 1.5.2 can be found available for free download here
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